Yes, Proton has fewer side effects on many types of treatments but not prostate cancer. It has been measured against IMRT as equally effective and similar side effects. Check the Partiqol study, note rectal effects chart year one, study says proton is worse but not significantly. Then look at recent SBRT, and especially MRI guided SBRT and I think side effect profile is much better. Worth the time to look at this information. Also prostatectomy at a younger age might be worth considering. I am not a doc so please do your own research.